Development of 3-D detailed FBR core calculation method based on method of characteristics

Takeda, Toshikazu*; Imai, Hideki*; Kitada, Takanori*; Nishi, Hiroshi; Ishibashi, Junichi; Kitano, Akihiro 

A new detailed 3-D transport calculation method taking into account the heterogeneity of fuel assemblies has been developed in hexagonal-z geometry by combining the method of characteristics and the nodal transport method. From the nodal transport calculation which uses assembly homogenized cross sections, the axial leakage is calculated, and it is used for the MOC calculation which treats the heterogeneity of fuel assemblies. Series of homogeneous MOC calculations which use assembly homogeneous cross sections are carried out of obtain effective cross sections, which preserve assembly reaction rates. This effective cross sections are again used in the 3-D nodal transport calculations. The numerical calculations have been performed to verify 3-D radial calculations of FBR assemblies and partial core calculations. Results are compared with the reference Monte-Carlo calculations. A good agreement has been achieved. It is shown that the present method has an advantage in calculating reaction tates in small region.